1. Field of the Invention
This invention relates generally to bearing assemblies utilizing a bushing, and pertains more particularly to a tapered holder for retaining the bushing within the rotatable member.
2. Description of the Prior Art
Extensive use is made of crawlers for supporting and propelling heavy-duty equipment, such as tractors, excavators, cranes, backhoes and drag lines. Conventionally, crawlers of this character include a pair of frame units, each having a driven tumbler at one end and an idler tumbler at the other end about which is entrained an endless track. Mounted to each frame unit between the tumblers are upper and lower rollers. The lower rollers bear against the ground-engaging stretch of endless track as it passes therebeneath to support the vehicle, whereas the upper rollers function mainly to guide the upper stretch of track as it passes thereover.
Although the weight of the vehicle is distributed over a number of lower rollers, each roller still must carry an appreciable load. Also, the sides of both the upper and lower rollers must be prevented from rubbing against the frame unit.
Therefore, it is common practice to use flanged bushings which are press fitted into the roller, the bushings encircling transverse shafts having their ends bolted to the frame unit. Owing to the heavy loads and rocking motion of the vehicle, these bushings wear quite rapidly. This accelerated wear necessitates frequent replacement of the bushings. Also, their flanges are vulnerable to wear because of the constant lateral shifting of the rollers on their respective shafts, thereby causing the flanges to be repeatedly thrust toward the sides of the frame unit. Although the flanges are designed to function as thrust bearings in the space between the roller and the sides of the frame unit, they nonetheless become misshapen and deformed from the constant rubbing that occurs. When the distortion has progressed sufficiently, the roller is prevented from rotating. When this happens, it has been necessary to replace the entire flanged bushing.
The flanged bushings, however, are press fitted into the roller, the press fit usually being on the order of from 0.006 to 0.007 inch. Such a tight fit requires that the removal be done at the shop. To do this, quite obviously, the entire vehicle must be transported, frequently over considerable distances, back to the shop in order to enable the replacement to be made. A considerable saving in time and effort would be effected if the replacement could be satisfactorily performed in the field, that is, at the site where the equipment is being used. Even though the currently used technique has proved extremely expensive, no practical solution to this problem has heretofore been presented to the construction industry.